The n-dimensional Laplace Equation

The n-dimensional Laplace equation is of the form:

$\displaystyle \nabla^{2}_{}$$\displaystyle \phi$ = $\displaystyle \phi_{x_1 x_1}^{}$ + $\displaystyle \phi_{x_2 x_2}^{}$ + ... + $\displaystyle \phi_{x_n x_n}^{}$ = 0

The determining systems for this equation are the simplest that we have posted Lie symmetry determining systems for.

The determining system consists of the dependent variables $ \Phi$ and X01, X02,..., Xn which depend on the independent variables $ \phi$ and x01, x02,..., xn.

The systems for n = 3..16 can be downloaded here (the files in the archive are named laplace_n). It should be emphasized that these are test systems only, as they are homogeneous constant coefficient PDE in the infinitesimals, and are relatively easy to bring to simplified form (as can be seen by the run-times below).



  Input   PureElim  
Dimension Equations Length Time (sec) Mem (MB)
3 34 2723 0.01 0.70
4 58 5027 0.02 0.72
5 88 8211 0.04 0.75
6 124 12395 0.08 0.78
7 166 17699 0.15 0.86
8 214 24243 0.23 0.89
9 268 32147 0.39 1.00
10 328 41531 0.70 1.24
11 394 52515 1.10 1.39
12 466 65219 1.73 1.59
13 544 79763 3.19 1.88
14 628 96267 5.09 2.72
15 718 114851 8.77 3.43
16 814 135635 14.22 3.92


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Allan Wittkopf 2000-06-15